Lubricant composition containing a viscosity index improver having dispersant properties

ABSTRACT

The present invention relates to a lubricant composition containing a minor amount of a thermally stable modified selectively hydrogenated alkenyl arene/conjugated diene copolymer wherein a primary or secondary amine functional group is grafted to the block copolymer primarily in the alkenyl arene blocks thereof.

CROSS-REFERENCE TO RELATED APPLICATIONS

This is related to copending U.S. patent application Ser. No. 766,217,filed Aug. 16, 1985.

FIELD OF THE INVENTION

This invention relates to novel selectively hydrogenated functionalizedblock copolymers. More particularly, it relates to a novel thermoplasticpolymer which when blended with engineering thermoplastics which arecondensation polymers, such as polyesters, polyurethanes and polyamides,is expected to enhance the impact toughness of articles made from suchblends. Additionally, these block copolymers are expected to findutility as viscosity index improvers and dispersants for lubricants,fuels and the like. The polymer is obtained by modifying a blockcopolymer composed of a selective-y hydrogenated conjugated dienecompound and an alkenyl arene compound with a primary or secondary aminecontaining functional group grafted primarily in the alkenyl areneblock.

BACKGROUND OF THE INVENTION

It is known that a block copolymer can be obtained by an anioniccopolymerization of a conjugated diene compound and an alkenyl arenecompound by using an organic alkali metal initiator. Block copolymershave been produced which comprise primarily those having a generalstructure

    A--B and A--B--A

wherein the polymer blocks A comprise thermoplastic polymer blocks ofalkenyl arenes such as polystyrene, while block B is a polymer block ofa selectively hydrogenated conjugated diene. The proportion of thethermoplastic blocks to the elastomeric polymer block and the relativemolecular weights of each of thcse blocks is balanced to obtain a rubberhaving unique performance characteristics. When the content of thealkenyl arene is small, the produced block copolymer is a so-calledthermoplastic rubber. In such a rubber, the blocks A arethermodynamically incompatible with the blocks B resulting in a rubberconsisting of two phases; a continuous elastomeric phase (blocks B) anda basically discontinuous hard, glass-like plastic phase (blocks A)called domains. Since the A--B--A block copolymers have two A blocksseparated by a B block, domain formation results in effectively lockingthe B blocks and their inherent entanglements in place by the A blocksand forming a network structure.

These domains act as physical crosslinks anchoring the ends of manyblock copolymer chains. Such a phenomena allows the A--B--A rubber tobehave like a conventionally vulcanized rubber in the unvulcanized stateand is applicable for various uses. For example, these network formingpolymers are applicable for uses such as moldings of shoe sole, etc.;impact modifier for polystyrene resins and engineering thermoplastics;in adhesive and binder formulations; modification of asphalt; etc.

Conversely, as the A-B block copolymers have only one A block, domainformation of the A blocks does not lock in the B blocks and theirinherent entanglements. Moreover, when the alkenyl arene content issmall resulting in a continuous elastomeric B phase. The strength ofsuch polymers is derived primarily from the inherent entanglements ofthe various B blocks therein and to a lesser extent the inherententanglements of the A blocks therein. However, the non-network formingpolymers have found particular utility as viscosity index improvers(U.S. Pat. Nos. 3,700,748; 3,763,044; 3,772,196; 3,965,019; and4,036,910). Non-network forming polymers are also utilized in adhesiveand binder formulations and as modifiers or plasticizers for polystyreneresins and engineering thermoplastics (U.S. Pat. No. 4,584,338).

Network forming copolymers with a high alkenyl arene compound content,such as more than 70% by weight, provide a resin possessing bothexcellent impact resistance and transparency, and such a resin is widelyused in the field of packaging. Many proposals have been made onprocesses for the preparation of these types of block copolymers (U.S.Pat. No. 3,639,517).

Both the network forming (A--B--A) and non-network forming (A--B)polymers are physically crosslinked, these polymers may be handled inthermoplastic forming equipment and are soluble in a variety ofrelatively low cost solvents.

While in general these block copolymers have a number of outstandingtechnical advantages, one of their principal limitations lies in theirsensitivity to oxidation. This behavior is due to the unsaturationpresent in the elastomeric section comprising the polymeric diene block.Oxidation may be minimized by selectively hydrogenating the copolymer inthe diene block, for example, as disclosed in U.S. Pat. Re. No. 27,145and the above referenced VI improver patents. For example, prior tohydrogenation, the block copolymers have an A--B or an A--B--A molecularstructure wherein each of the A's is an alkenyl-arene polymer block andB is a conjugated diene polymer block, such as an isoprene polymer blockor a butadiene polymer block preferably containing 35-55 mole percent ofthe condensed butadiene units in a 1,2 configuration.

Non-network forming (A--B) block copolymers are especially deficient inapplications in which good mechanical integrity and deformationresistance are required. This behavior is a consequence of the lack ofinherent entanglements of the various B rubber blocks and to a lesserextent the entanglements of the A blocks therein which controls strengthunder tensile deformation. Additionally, these non-network formingcopolymers, in particular A--B copolymers, are also deficient inviscosity index (Vl) improver applications wherein thickening efficiencyis lost at higher temperatures. As such, improvement in such propertiesmay be achieved by enhancing the integrity of the alkenyl arene domainsand the elastomeric matrix through the incorporation of interactingfunctional groups along the polymer chain.

Conversely, network forming copolymers are known to have particularlyhigh tensile strengths at room temperature due to the formation ofglassy phase arene block domains which act as physical crosslinkslocking in the inherent entanglements within the rubbery B block matrix.The mechanical integrity of these domains and the resulting networkstructure formed appear to control the tensile strengths of thesecopolymers. Moreover, at elevated temperatures, the mechanical integrityof block copolymers is limited to the integrity of the hard phase areneblock domains. For example, network forming copolymers having areneblocks of polystyrene have poor mechanical properties at hightemperature which may be attributed to the weakening of the polystyrenedomains above its glass transition temperature (Tg) of 100° C.Improvements in the high temperature characteristics of the networkforming block copolymers may be achieved by enhancing the integrity ofthe alkenyl arene domains to higher temperatures.

These selectively hydrogenated block copolymers are further deficient inmany applications in which interactions are required between it andother materials. Applications in which improvements in adhesioncharacteristics may promote improved performance include (1) thetoughening of, and dispersion in, polar polymers such as the engineeringthermoplastics; (2) the adhesion to high energy substrates in ahydrogenated block copolymer elastomer based high temperature adhesive,sealant or coating materials; and (3) the use of hydrogenated elastomersin reinforced polymer systems. The placement of functional groups ontothe block copolymer may provide interactions not possible withhydrocarbon polymers and, hence, may extend the range of applicabilityof this material.

Many attempts have been made to improve the impact properties ofpolyamides by adding low modulus modifiers which contain polar moietiesas a result of polymerization or which have been modified to containpolar moieties by various grafting techniques. To this end, variouscompositions have been proposed utilizing such modifiers having nitrogencontaining functional groups thereon, for example, Epstein in U.S. Pat.No. 4,174,358; Hergenrother et al. in U.S. Pat. No. 4,427,828; andBeever et al. in U.S. Pat. No. 4,588,756.

Epstein discloses a broad range of low modulus polyamide modifiers whichhave been prepared by free radical copolymerization of specific monomerswith acid containing monomers. Alternatively, Epstein discloses themodification of polymers by grafting thereto specific carboxylic acidcontaining monomers. The grafting techniques allowed for therein arelimited to thermal addition (ene reaction) and to nitrene insertion intoC-H bonds or addition to C═C bonds (ethylenic unsaturation). Via thesegrafting techniques, Epstein may produce modifiers withnitrogen-containing functional groups. With nitrene insertion, thearomatic sulfonyl azides utilized therein are used as a means forgrafting a carboxylic acid group onto the modifier. As such, theinteraction between the polyamide and the modifier is achieved via thecarboxylic acid group of these nitrogen containing functional groups. Onthe otherhand, when a dicarboxylic acid or derivative thereof (e.g., ananhydride) group is grafted thereon say via thermal addition, thedicarboxylic acid group may either directly interact with the polyamidevia a grafting reaction or indirectly interact with the polyamide byfirst further modifying the dicarboxylic acid group by reacting samewith a caprolactam to form a cyclic imide with a pendant polyamideoligomer chain which in turn acts as a compatibilizer with the polyamideor possible transamidation graft site.

Though Epstein does disclose a broad range of polyamide modifiers,Epstein does not disclose or suggest the utilization of hydrogenatedcopolymers of alkenyl arenes and conjugated dienes nor, moreparticularly, modified selectively hydrogenated copolymers of alkenylarenes and conjugated dienes as polyamide modifiers. Furthermore,Epstein relies upon the carboxylic acid portion, as opposed to thenitrogen portion, of the functional groups in the modifiers therein asthe active participant in the impact modification of the polyamide.

Hergenrother et al. disclose polyamide compositions which contain amodified partially hydrogenated aromatic vinyl compound/conjugated dieneblock copolymer as a polyamide modifier. In order to improve theweatherability and resistance to heat aging, Hergenrother et al.partially hydrogenate the block copolymer in their respective blends toan ethylenic unsaturation degree not exceeding 20 percent of theethylenic unsaturation contained in the block copolymer prior tohydrogenation. Once the block copolymer is partially hydrogenated, theblock copolymer is modified by grafting a dicarboxylic acid group orderivative thereof (e.g. anhydride moieties). Hergenrother et al.disclose grafting via thermal addition (ene reaction) utilizing theavailable residual unsaturation in the block copolymer. As such,Hergenrother et al. retained the deficiencies associated with thereversibility of the ene reaction. The anhydride moieties therein, likein Epstein, are believed to undergo a grafting reaction with theterminal amines of the polyamide to form a cyclic imide, therebyconverting the functional group into a nitrogen-containing functionalgroup. However, it is readily apparent that Hergenrother et al. placeheavy reliance on these anhydride moieties, as opposed to anitrogen-containing functional group, to effect the impact modificationof the polyamide.

As is readily apparent from the foregoing prior art polyamidecompositions utilizing alkenyl arene/conjugated diene block copolymersas polyamide modifiers, improved impact modification of the particularpolyamide is achieved via specific interactions, between the modifieddiene block and the polyamide. Thus, to the extent that impactmodification and strength mechanisms rely on the elastomeric propertiesof the diene block of the copolymer, these properties have beenadversely affected by modifying the diene block in this manner.

Beever discloses a polyamide composition containing an oil-solubleorganonitrogen compound grafted hydrogenated conjugateddiene/monovinylarene copolymer, such as those described in U.S. Pat. No.4,145,298 to Trepka. The copolymer is characterized as having beenprepared by the process which comprises (1) metalating a hydrogenatedconjugated diene hydrocarbon/mono vinylarene hydrocarbon copolymer and(2) reacting the resulting metalated hydrogenated copolymer witheffective amounts of at least one nitrogen-containing organic compound,thereby preparing the grafted copolymer. The suitable nitrogencontaining organic compound are specifically described by the generalformula:

    X--Q--(NR.sub.2.sup.3).sub.n or Y--Q--(NR.sub.2.sup.3).sub.n ].sub.m

wherein each R₂ ³ is the same or different alkyl, cycloalkyl, aryl, orcombination thereof, Q is a hydrocarbon radical having a valence of n+1and is a saturated aliphatic, saturated cycloaliphatic, or aromaticradical, or combination thereof, X is a functional group capable ofreacting on a one-to-one basis with one equivalent of polymer lithium, Yis or contains a functional group capable of reacting on a one-to-onebasis with one equivalent of polymer lithium, n is at least one, and mis 2 or 3. X includes: ##STR1## wherein R⁴ is hydrogen, or an alkyl,cycloalkyl, or aryl radical or combination radical; N.tbd.C--; and R³N═CH--. Thus, it is readily apparent that suitable nitrogen-containingorganic compounds therein are electrophilic graftable moleculesrequiring three portions: (1) X, a lithium reactive functional group;(2) NR₂ ³, the nitrogen containing portion of the molecule (a tertiaryamine); and (3) Q, which couple together X and NR₂ ³. This method ofusing an electrophilic graftable molecule having an appended amine siteas a route to attach amine groups to the block copolymer suffers fromthe disadvantage that the product of the reaction of X with thelithiated polymer is itself a functional site (a ketone or alcohol forexample). The introduction of this second (reactive) site offunctionality (with the amine being the other site of functionality) maylead to undesirable effects particularly in the process of Incorporatingthe required amine functionality.

With respect to viscosity index improvers, many attempts have been madeto improve the viscosity index of lubricants and the like by addingmodifiers which contain polar moieties as a result of various graftingtechniques. The incorporation of nitrogen-containing functional groupsonto the modifiers imparts thereto dispersant characteristics inlubricants, fuels and the like. To this end, various viscosity indeximprover/dispersant modifiers have been proposed havingnitrogen-containing functional groups thereon, for example, Kiovsky inG.B. Pat. No. 1,548,464, Hayashi et al in U.S. Pat. No. 4,670,173, andTrepka in U.S. Pat. Nos. 4,145,298 and 4,328,202.

Both Kiovsky and Hayashi et al. disclose a partially or selectivelyhydrogenated aromatic vinyl compound/conjugated diene block copolymer towhich has been grafted a carboxylic acid group (or anhydride thereof)onto the diene portion of the polymer. The graft is effected via a freeradically initiated reaction. Once modified with carboxyl functionalgroups, the modified polymer is further modified by reacting thesecarboxyl or functional groups with an amine containing material, e.g. amono- or polyamine. The so modified polymer contains anitrogen-containing functional group to impart dispersingcharacteristics thereto.

Trepka discloses an oil-soluble organonitrogen compound graftedhydrogenated conjugated diene/monovinylarene copolymer. This samepolymer is utilized to impact modify polyamides by Beever et al. in U.S.Pat. No. 4,588,756, previously discussed herein. The disadvantages ofutilizing such a polymer for impact modifying polyamides are equallyapplicable with respect to viscosity index improver and dispersantapplications. Of particular importance is the disadvantage related tothe introduction of a second (reactive) site of functionality (a ketoneor alcohol for example) with the amine being the other site offunctionality. This second functional site is particularly susceptibleto oxidative attack and cleavage of the amine functional group from thepolymer, particularly under the severe conditions encountered in aninternal combustion engine. Such an occurrence would be expected tosignificantly reduce the dispersant activity of the polymer.

On the otherhand, the present invention relates to a thermally stable,modified, selectively hydrogenated conjugated diene/alkenyl arenecopolymer grafted with at least one functional group utilizing themetalation process. Herein, the functional groups are amine functionalgroups which are grafted primarily in the alkenyl arene portions of thecopolymer. The introduction of a second site of functionality is avoidedby utilizing electrophiles, as opposed to electrophilic graftablemolecules such as in Beever. The electrophiles are imines which becomesamine functional groups upon reacting with the lithiated polymer andcontacting with a proton source. In this composition, interactionsbetween a condensation polymer and the copolymer are expected to beachieved via the alkenyl arene block.

To those skilled in the art, the degree to which the grafting reactionand phase size reduction occur, thereby promoting interfacial adhesion,together with the distribution of the rubber within the blend typicallycontribute to impact toughening of the blend. The expected resultsherein are that functionalizing the alkenyl arene segment will promotecovalent bonding between the modified block copolymer and thecondensation engineering thermoplastic (ETP), polymers, e.g. apolyamide. Furthermore, the block copolymer is also expected to becomewell distributed in the polyamide phase.

SUMMARY OF THE INVENTION

According to the present invention, there is provided a thermallystable, selectively hydrogenated, block copolymer to which an aminefunctional group has been grafted primarily in the alkenyl arene block.

More specifically, there is provided a lubricant composition comprising:

(a) a major amount of a lubricating oil, and

(b) a minor effective viscosity improving amount of an oil soluble,functionalized selectively hydrogenated block copolymer to which hasbeen grafted a primary or secondary amine functional group, saidfunctionalized block copolymer comprising

(1) a base block copolymer which comprises

(i) at least one polymer block A, said A block being at leastpredominantly a polymerized alkenyl arene block, and

(ii) at least one selectively hydrogenated polymer block B, said B blockprior to hydrogenation being at least predominantly a polymerizedconjugated diene block,

(2) wherein substantially all of said amine functional groups aregrafted to said base block copolymer on said A blocks.

The functionalized block copolymer is preferably characterized as havingbeen prepared by the process which comprises

(i) metalating the base block copolymer;

(ii) reacting the resulting metalated base block copolymer with at leastone imine wherein the imine is represented by the general formula##STR2## where R₁, R₂, and R₃ are alkyl, cycloalkyl or aryl radicals ora combination thereof; and

(iii) contacting the resulting metalated amine with a proton source,such as water or a dilute aqueous acid, thereby preparing thefunctionalized block copolymer. R₁, R₂ and R₃ may be the same ordifferent radical. Additionally, R₃ may be a hydrogen or a silyl radicalrepresented by the general formula: ##STR3## wherein R₅, R₆ and R₇ arethe same or different alkyl, cycloalkyl or aryl radicals or acombination thereof, for example, methyl, ethyl, phenyl, etc. There isno known limit on the number of carbon atoms of any of R₁, R₂, R₃, R₅,R₆ or R₇ as far as operability is concerned. Such radicals withoutacidic hydrogen atoms thereon are particularly preferred to avoid thepossibility of deleterious protonation of the metalated (e.g. lithiated)polymer.

Furthermore, the functionalized block copolymer may be linear orbranched, with the term "branched" also including symmetric orasymmetric radial and star structures.

Preferably, there is provided the functionalized selectivelyhydrogenated block copolymer as defined above, wherein

(a) each of the A blocks prior to hydrogenation is at leastpredominantly a polymerized monoalkeny monocyclic arene block having anaverage molecular weight of about 1,000 to about 125,000, preferablyabout 1,000 to about 60,000,

(b) each of the B blocks prior to hydrogenation is at leastpredominantly a polymerized conjugated diene block having an averagemolecular weight of about 10,000 to about 450,000, preferably about10,000 to about 150,000,

(c) the A blocks constitute between about 1 and about 99, preferablybetween about 2 and about 70, and more preferably between about 20 andabout 70 percent by weight of the copolymer,

(d) the unsaturation of the B blocks is less than about 10 percent,preferably less than about 5 percent and more preferably at most 2percent, of the original unsaturation of the B blocks,

(e) the unsaturation of the A blocks is greater than about 50 percent,preferably greater than about 90 percent, of the original unsaturationof the A blocks, and

(f) the amine functional group is preferably present on the average fromabout one (1) of said amine functional groups per molecule of saidcopolymer :o about one (1) of said amine functional groups per aromaticring of said A block and more preferably on the average from about three(3) of said amine functional groups per molecule of said copolymer toabout one (1) of said amine functional groups per aromatic ring of saidA block.

For imparting suitable dispersancy to the block copolymers, theeffective amount of nitrogen grafted thereto is at least about 0.01percent by weight based on the base block copolymer, more preferablyfrom about 0.01 to about 5 percent by weight and yet more preferablyfrom about 0.05 to about 0.5 percent by weight.

An effective amount of the functionalized block copolymer herein fordispersing insoluble impurities and for improving viscosity propertiesnormally will be from about 0.01 to about 10 percent by weight based onthe total weight of the lubricant, preferably from about 0.5 to about 5percent by weight.

Preferably, these block copolymers are diluted with a substantiallyinert, normally liquid organic diluent to form concentrates. Theseconcentrates usually contain from about 5 percent to about 90 percent byweight of the functionalized block copolymer based on the total weightof the concentrate.

A feature of this invention lies in providing modified block copolymerswhich are thermally stable; have a low residual unsaturation; areprocessable in solution and/or in the melt; are expected to haveimproved mechanical properties at room and elevated temperatures overits respective precursor (unmodified) block copolymer, such as tensilestrength, and deformation resistance; etc.

Another feature of this invention lies in providing modified blockcopolymers which are expected to improve the impact resistance ofengineering thermoplastics which are condensation products , such aspolyesters, polyamides and polyurethanes, when blended therewith.

Yet another feature of this invention lies in providing modified blockcopolymers which are expected to provide viscosity index improvement inlubricants and the like and dispersancy in lubricants, fuels and thelike.

Accordingly, these and other features and advantages of the presentinvention will become apparent from the following detailed description.

DETAILED DESCRIPTION OF THE INVENTION Selectively Hydrogenated BlockCopolymer Base Polymer

The selectively hydrogenated block copolymers employed in the presentinvention may have a variety of geometrical structures, since theinvention does not depend on any specific geometrical structure, butrather upon the chemical constitution of each of the polymer blocks, andsubsequent modification of the block copolymer. The precursor of theblock copolymers employed in the present composition are preferablythermoplastic elastomers and have at least one alkenyl arene polymerblock A and at least one elastomeric conjugated diene polymer block B.The number of blocks in the block copolymer is not of special importanceand the macromolecular configuration may be linear or branched, whichincludes graft, radial or star configurations, depending upon the methodby which the block copolymer is formed.

Typical examples of the various structures of the precursor blockcopolymers used in the present invention are represented as follow:

    (A--B)n

    (A--B)n A

    (B--A)n B

    [(A--B)p]m X

    [(B--A)p]m X

    [(A--B)pA]m X

and

    [(B--A)p B]m X

wherein A is a polymer block of an alkenyl arene, B is a polymer blockof a conjugated diene, X is a residual group of a polyfunctionalcoupling agent having two or more functional groups, n and p are,independently, integers of 1 to 20 and m is an integer of 2 to 40.Furthermore, the above-mentioned branched configurations may be eithersymmetrical or asymmetrical with respect to the blocks radiating from X.

A specific subset of the foregoing precursor block copolymers are thenon-network forming block copolymers. Once modified pursuant to thepresent invention, such modified block copolymers are expected to beexcellent viscosity index improvers with dispersancy characteristics andare also expected to impact modify engineering thermoplastics which arecondensation products.

"Non-network forming block copolymers" means those polymers havingeffectively only one alkenyl arene polymer block A. Structuralconfigurations included therein are represented as follows:

    B--A                                                       (1)

    B--A--B                                                    (2)

    (B--A).sub.n X                                             (3)

    (B--A).sub.y X--B).sub.z                                   (4)

wherein A is a polymer block of an alkenyl arene, B is a polymer blockof a conjugated diene, X is a residual group of a polyfunctionalcoupling agent having two or more functional groups, y and z are,independently, integers of 1 to 20 and n is an integer of 2 to 40.Furthermore, the above-mentioned branched configurations may be eithersymmetrical or asymmetrical with respect to the blocks radiating from X.

As is readily apparent from the foregoing structures, there is"effectively" only one alkenyl arene polymer block A. In structures (1)and (2) there is only one block A in each. In structures (3) and (4),each of the blocks A are molecularly attached to each other via apolyfunctional coupling agent and as such is in effect only one block Awith B blocks radiating out therefrom. Thus, the network structureformed by A--B--A type polymers utilizing the domains is not possible inthese non-network forming block copolymers. Typical block copolymers ofthe most simple configuration (structure (1) above) would bepolystyrene-polybutadiene (S-B) and polystyrene-polyisoprene (S-I).

It will be understood that both blocks A and B may be eitherhomopolymer, random or tapered copolymer blocks as long as each block atleast predominates in at least one class of the monomers characterizingthe blocks defined hereinbefore. For example, blocks A may comprisestyrene/alphamethylstyrene copolymer blocks or styrene/butadiene randomor tapered copolymer blocks as long as the blocks individually at leastpredominate in alkenyl arenes. The A blocks are preferably monoalkenylarene. The term "monoalkenyl arene" will be taken to includeparticularly those of the benzene series such as styrene and its analogsand homologs including o-methylstyrene, p-methylstyrene,p-tert-butylstyrene, 1,3-dimethylstyrene, alpha-methylstyrene and otherring alkylated styrenes, particularly ring-methylated styrenes, andother monoalkenyl polycyclic aromatic compounds such as vinylnaphthalene, vinyl anthracene and the like. The preferred monoalkenylarenes are monovinyl monocyclic arenes such as styrene andalphamethylstyrene, and styrene is particularly preferred.

The blocks B may comprise homopolymers of conjugated diene monomers,copolymers of two or more conjugated dienes, and copolymers of one ofthe dienes with a monoalkenyl arene as long as the blocks B at leastpredominate in conjugated diene units. The conjugated dienes arepreferably ones containing from 4 to 8 carbon atoms. Examples of suchsuitable conjugated diene monomers include: 1,3-butadiene (butadiene),2-methyl-1,3-butadiene (isoprene), 2,3-dimethyl-1,3-butadiene,1,3-pentadiene (piperylene), 1,3-hexadiene, and the like. Mixtures ofsuch conjugated dienes may also be used. The preferred conjugated dienesare butadiene and isoprene.

Preferably, the block copolymers of conjugated dienes and alkenyl arenehydrocarbons which may be utilized include any of those which exhibitelastomeric properties; and those butadiene derived elastomers whichhave 1,2-microstructure contents prior to hydrogenation of from about 7to about 100 percent, preferably from ahout 25 to about 65 percent, morepreferably from about 35 to ahout 55 percent. Such block copolymers maycontain various ratios of conjugated dienes to alkenyl arenes. Theproportion of the alkenyl arene blocks is between about 1 and about 99percent by weight of the multiblock copolymer, preferably between aboutZ and about 60 percent, more preferably between about 2 and about 55percent by weight and particularly preferable between about 2 and about40 percent by weight. When the alkenyl arene content is not more thanabout 60 percent by weight, preferably not more than about 55 percent byweight, the precursor block copolymer has characteristics as athermoplastic elastomer; and when the alkenyl arene content is greaterthan about 60 percent by weight, preferably more than about 70 percentby weight, the precursor block copolymer has characteristics as aresinous polymer.

For viscosity index improving purposes, the alkenyl arene content rangesfrom about 2 to about 70 and preferably from about 20 to about 70percent by weight.

The average molecular weights of the individual blocks may vary withincertain limits. In most instances, the monoalkenyl arene blocks willhave average molecular weights in the order of about 1,000 to about125,000, preferably about 1,000 to about 60,000, while the conjugateddiene blocks either before or after hydrogenation will have averagemolecular weights on the order of about 10,000 to about 450,000,preferably about 10,000 to about 150,000. The total average molecularweight of the multiblock copolymer is typically on the order of about11,000 to about 2,500,000. These molecular weights are most accuratelydetermined by gel permeation chromatography or by gel permeation-lowangle light scattering.

The block copolymer may be produced by any well known blockpolymerization or copolymerization procedures including the well knownsequential addition of monomer techniques, incremental addition ofmonomer technique or coupling technique as illustrated in, for example,U.S. Pat. Nos. 3,251,905; 3,390,207; 3,598,887 and 4,219,627, which areincorporated herein by reference. As is well known in the blockcopolymer art, tapered copolymer blocks can be incorporated in themultiblock copolymer by copolymerizing a mixture of conjugated diene andalkenyl arene monomers utilizing the difference in theircopolymerization reactivity rates. Various patents describe thepreparation of multiblock copolymers containing tapered copolymer blocksincluding U.S. Pat. Nos. 3,251,905; 3,265,765; 3,639,521 and 4,208,356the disclosures of which are incorporated herein by reference.Additionally, various patents describe the preparation of symmetric andasymmetric radial and star block copolymers including U.S. Pat. Nos.3,231,635; 3,265,765; 3,322,856; 4,391,949; and 4,444,953; thedisclosure of which patents are incorporated herein by reference.

Though the afore-mentioned illustrative patents are slanted to producingnetwork forming block copolymers (e.g. A--B--A), the non-network formingblock copolymers of the present application may be prepared by anobvious variation or modification of these procedures; for example, (1)sequential polymerization of an A--B or B--A--B block copolymer; (2)utilizing a di-initiator to prepare a B--A--B block copolymer; (3)utilizing polyfunctional coupling agents to couple B--A--Li livingcopolymer segments to form a (B--A)_(n) X polymer, where X is theresidual portion of the polyfunctional coupling agent incorporated aspart of the polymer whose presence therein is of insignificant effect tothe properties of the resulting polymer and where n is the number ofblock copolymer segments or arms attached to X; and (4) similarlyutilizing polyfunctional coupling agents to couple B--A--Li livingcopolymer segments and B--Li living homopolymer or diene copolymersegments to form a (B--A--_(y) X--B)_(z) polymer, where X is as beforeand y and z represent the number of respective segments or arms attachedto X.

It should be observed that the above-described polymers and copolymersmay, if desired, be readily prepared by the methods set forth above.However, since many of these polymers and copolymers are commerciallyavailable, it is usually preferred to employ the commercially availablepolymer as this serves to reduce the number of processing steps involvedin the overall process.

These polymers and copolymers are preferably hydrogenated to increasetheir thermal stability and resistance to oxidation. The hydrogenationof these polymers and copolymers may be carried out by a variety of wellestablished processes Including hydrogenation in the presence of suchcatalysts as Raney Nickel, noble metals such as platinum, palladium andthe like and soluble transition metal catalysts. Suitable hydrogenationprocesses which can be used are ones wherein the diene-containingpolymer or copolymer is dissolved in an inert hydrocarbon diluent suchas cyclohexane and hydrogenated by reaction with hydrogen in thepresence of a soluble hydrogenation catalyst. Such processes aredisclosed in U.S. Pat. Nos. Re. 27,145; 3,113,986; 3,700,633; 3,700,748;3,763,044; 3,772,196; 3,965,019; 4,036,910; and 4,226,952, thedisclosures of which are incorporated herein by reference. The polymersand copolymers are hydrogenated in such a manner as to producehydrogenated polymers and copolymers having a residual ethylenicunsaturation content in the polydiene block of not more than about 20percent, preferably less than about 10 percent, more preferably lessthan about 5 percent and yet more preferably at most about 2 percent, oftheir original ethylenic unsaturation content prior to hydrogenation.

Modified Block Copolymers

The modified block copolymers according to the present invention arePreferably grafted or substituted in the alkenyl arene block by themetalation process as later described herein. Exemplary metalationreactions are given below, utilizing an exemplary styrene unit from apolystyrene segment of a suitable block copolymer: ##STR4## Anelectrophile, such as an imine is subsequently reacted with themetalated block copolymer and quenched (contacted) with a proton sourceto yield primary or secondary amine functional groups at theabove-indicated metalated sites.

The structure of the substituted block copolymer specifically determinedby locating the functionality on the alkenyl arene block gives the blockcopolymer a substantially greater degree of thermal stability.

GraftabIe Compounds

In general, any materials having the ability to react with the metalatedbase polymer are operable for the purposes of this invention.

In order to incorporate functional groups Into the metalated basepolymer, electrophiles capable of reacting with the metalated basepolymer are necessary. Reactants may be polymerizable ornonpolymerizable; however, preferred electrophiles are nonpolymerizablewhen reacted with metalated polymers such as those utilized herein.

There are many electrophiles and electrophilic graftable molecules thatare (1) capable of reacting with a lithiated block copolymer and (2)contain an amine functional site. As an example, consider an N,N-dialkylamino-acid ester, an electrophilic graftable molecule. The electrophilicsite in ##STR5## this exemplary molecule is the ester moiety ##STR6##which would be expected to react with the lithiated polymer affording aketone ##STR7## with the appended tertiary amine site ##STR8## Thismethod of using an electrophilic graftable molecule having an appendedamine site as a route to attach amine groups to the block copolymersuffers from the disadvantage that the product of the reaction of theelectrophilic portion of the molecule with the lithiated polymer isitself a functional site ##STR9## a ketone in this example). In someapplications it is undesirable to introduce this second site offunctionality in the process of incorporation of the amine.

A method for the direct incorporation of an amine would involve thereaction of the lithiated polymer with a suitable imine (see "TheChemistry of Organolithium Compounds," B. J. Wakefield, Pergamon Press,Oxford, England, p. 109). ##STR10## where R₁, R₂ and R₃ are alkyl,cycloalkyl or aryl radicals. Additionally, R₃ may be a hydrogen or asilyl radical, such as --Si(CH₃)₃, --Si--(CH₂ --CH₃)₃ and --Si--(C₆H₅)₃. As shown in the above equation, this method would introduce anamine functional site (in particular, a primary or secondary aminefunctional site) without the undesirable side effect of introducing asecond functional species.

A block copolymer having a primary or secondary amine functional siteswould be expected to react with a condensation polymer, such aspolyesters, polyamides, and polyurethanes, via a nucleophilicsubstitution reaction at an activated carboxyl carbon center as found inmany condensation polymers, for example, via the transamidation reactionas outlined below. Suitable polyesters, polyamides, and polyurethanesare disclosed in U.S. Pat. Nos. 4,080,357; 4,429,076; 4,628,072;4,657,970; and 4,657,971, the disclosure of which are hereinincorporated by reference. ##STR11## where the wavy lines represent therest of the polyamide chain in a simplified manner. (see "AdvancedOrganic Chemistry-Reactions, Mechanisms, and Structure," 3rd Ed., J.March, John Wiley & Sons, New York, 1985, p. 376 and referencestherein). In this way, a nylon polymer could be covalently grafted ontothe modified block copolymers. It is noted at this point that theforegoing reaction requires a primary or secondary amine--a tertiaryamine would be inoperative.

The quantity of amine functional groups in the modified block copolymeris dependent on the content and the aromatic structure of the alkenylarene therein. Once these parameters are fixed, the number of suchgroups present is dependent on the degree of functionality desiredbetween a minimum and maximum degree of functionality based on theseparameters. The minimum degree of functionality corresponds on theaverage at least about one (1), preferably at least about three (3),amine functional groups per molecule of the block copolymer. It ispresently believed that the addition of about one (1) electrophile peraromatic ring of the A blocks is limiting. Thus, if the electrophileimine (R₁ R₂ C═NR₃) which contains only one amine functional group isused, this translates to about one (1) amine group per aromatic ring asa maximum functionality level. Preferably, the functionality level is onthe average from about one (1) amine functional groups per molecule ofthe copolymer to about one amine functional group per aromatic ring ofthe A block, and more preferably on the average from about three (3)amine functional groups per molecule of the copolymer to about one aminefunctional group per aromatic ring of the A block.

The block copolymers, as modified, may still be used for any purpose forwhich an unmodified material (base polymer) was formerly used. That is,they may be used for adhesives and sealants, modifiers for lubricants,fuels and the like, or compounded and extruded and molded in anyconvenient manner.

Preparation of the modified Block Copolymers

The polymers may be prepared by any convenient manner. Preferably, thepolymer is prepared such that the functional groups are incorporatedinto the block copolymer primarily on the aromatic portion of thealkenyl arene block via metalation.

Metalation may be carried out by means of a complex formed by thecombination of a lithium component which can be represented byR'(Li)_(x) with a polar metalation promoter. The polar compound and thelithium component can be added separately or can be premixed orpre-reacted to form an adduct prior to addition to the solution of thehydrogenated copolymer. In the compounds represented by R'(Li)_(x), theR' is usually a saturated hydrocarbon radical of any length whatsoever,but ordinarily containing up to 20 carbon atoms, and may also be asaturated cyclic hydrocarbon radical of e.g. 5 to 7 carbon atoms. In theformula R'(Li)_(x), x is an integer of 1 to 3. Representative speciesinclude, for example: methyllithium, isopropyllithium, sec-butyllithium,n-butyllithium, t-butyllithium, n-dodecyllithium, 1,4-dilithiobutane,1,3,5-trilithiopentane, and the like. The lithium alkyls must be morebasic than the product metalated polymer alkyl. Of course, other alkalimetal or alkaline earth metal alkyls may also be used; however, thelithium alkyls are presently preferred due to their ready commercialavailability. In a similar way, metal hydrides may also be employed asthe metalation reagent but the hydrides have only limited solubility inthe appropriate solvents. Therefore, the metal alkyls are preferred fortheir greater solubility which makes them easier to process.

Lithium compounds alone usually metalate copolymers containing aromaticand olefinic functional groups with considerable difficulty and underhigh temperatures which may tend to degrade the copolymer. However, inthe presence of tertiary diamines and bridgehead monoamines, metalationproceeds rapidly and smoothly.

Generally, the lithium metalates the position allylic to the doublebonds in an unsaturated polymer. In the metalation of polymers in whichthere are both olefinic and aromatic groups, the metalation will occurin the position in which metalation occurs most readily, as in positions(1) allylic to the double bond (2) at a carbon to which an aromatic isattached, (3) on an aromatic group, or (4) in more than one of thesepositions. In the metalation of saturated polymers having aromaticgroups as is preferably the case herein, the metalation will occurprimarily on an aromatic group and as a minor product at a carbon towhich an aromatic is attached. In any event, it has been shown that avery large number of lithium atoms are positioned variously along thepolymer chain, attached to internal carbon atoms away from the polymerterminal carbon atoms, either along the backbone of the polymer or ongroups pendant therefrom, or both, in a manner depending upon thedistribution of reactive or lithiatable positions. This distinguishesthe lithiated copolymer from simple terminally reactive polymersprepared by using a lithium or even a polylithium initiator inpolymerization thus limiting the number and the location of thepositions available for subsequent attachment. With the metalationprocedure described herein, the extent of the lithiation will dependupon the amount of metalating agent used and/or the groups available formetalation. The use of a more basic lithium alkyl such astert-butyllithium alkyl may not require the use of a polar metalationpromoter.

The polar compound promoters include a variety of tertiary amines,bridgehead amines, ethers, and metal alkoxides.

The tertiary amines useful in the metalation step have three saturatedaliphatic hydrocarbon groups attached to each nitrogen and include, forexample:

(a) Chelating tertiary diamines, preferably those of the formula R₂N--(CH₂ --_(y) NR₂ in which each R can be the same or different,straight- or branched-chain alkyl group of any chain length containingup to 20 carbon atoms, or more, all of which are included herein and ycan be any whole number from 2 to 10, and particularly the ethylenediamines in which all alkyl substituents are the same. These include,for example: tetramethylethylenediamine, tetraethylethylenediamine,tetradecylenediamine, tetraoctylhexylenediamine, tetra-(mixed alkyl)ethylene diamines, and the like.

(b) Cyclic diamines can be used, such as, for example, theN,N,N',N'-tetraalkyl 1,2-diamino cyclohexanes, the N,N,N',N'-tetraalkyl1,4-diamino cyclohexanes, N,N'-dimethylpiperazine, and the like.

(c) The useful bridgehead diamines include, for example, sparteine,triethylenediamine and the like.

Tertiary monoamines such as triethylamine are generally not as effectivein the lithiation reaction. However, bridgehead monoamines such as1-azabicyclo[2.2.2]octane and its substituted homologs are effective.

Ethers and the alkali metal alkoxides are presently less preferred thanthe chelating amines as activators for the metalation reaction due tosomewhat lower levels of incorporation of functional group containingcompounds onto the copolymer backbone in the subsequent graftingreaction.

In general, it is most desirable to carry out the lithiation reaction inan inert solvent such as saturated hydrocarbons. Aromatic solvents suchas benzene are lithiatabIe and may interfere with the desired lithiationof the hydrogenated copolymer. The solvent/copolymer weight ratio whichis convenient generally is in the range of about 5:1 to about 20:1.Solvents such as chlorinated hydrocarbons, ketones, and alcohols, shouldnot be used because they destroy the lithiating compound.

Polar metalation promotors may be present in an amount sufficient toenable metalation to occur, e.g. amounts between about 0.01 and about100 or more preferably between about 0.1 to about 10 equivalents perequivalent of lithium alkyl.

The equivalents of lithium employed for the desired amount of lithiationgenerally range from such as about 0.001 to about 3.0 per alkenyl arenehydrocarbon unit in the copolymer, presently preferably about 0.01 toabout 1.0 equivalents per alkenyl arene hydrocarbon unit in thecopolymer to be modified. The molar ratio of active lithium to the polarpromoter can vary from such as about 0.01 to about 10.0. A preferredratio is about 0.5 to about 2.0.

The amount of lithium alkyl employed can be expressed in terms of thelithium alkyl to alkenyl arene hydrocarbon molar ratio. This ratio mayrange from a value of 1 (one lithium alkyl per alkenyl arene hydrocarbonunit) to as low as 1×10⁻³ (1 lithium alkyl per 1000 alkenyl arenehydrocarbon units).

The process of lithiation can be carried out at temperatures in therange of such as about -70° C. to about +150° C., presently preferablyin the range of about 25° C. to about 75° C., the upper temperaturesbeing limited by the thermal stability of the lithium compounds. Thelower temperatures are limited by considerations of production cost, therate of reaction becoming unreasonably slow at low temperatures. Thelength of time necessary to complete the lithiation and subsequentreactions is largely dependent upon mixing conditions and temperature.Generally, the time can range from a few seconds to about 72 hours,presently preferably from about 1 minute to about 1 hour.

Grafting Step

The next step in the process of preparing the modified block copolymeris the treatment of the lithiated hydrogenated copolymer, in solution,without quenching in any manner which would destroy the lithium sites,with a species capable of reacting with a lithium anion. These speciesare selected from the class of molecules called electrophiles and mustcontain functional groups capable of undergoing nucleophilic attack by alithium anion. Specifically, the electrophiles called imines whichbecome the desired amine are of interest in the present invention. Assuch, the modified block copolymer herein is the reaction product of anelectrophile with an activated base (unmodified hydrogenated) blockcopolymer primarily at lithium anion sites on the aromatic substratesthereof, as opposed to the reaction product of an electrophile (strongLewis acid) with an unactivated base block copolymer on the aromaticsubstrates thereof.

Preparation of Blends with Engineering Thermoplastics

The toughened thermoplastic polymer compositions of the presentinvention can be readily prepared by using any conventional mixingapparatus which is normally used for mixing or blending of polymersubstances. Examples of such apparatus are single or multiple screwextruders, mixing rollers, Brabender, Banbury mills, kneaders and thelike. Alternatively, the blends may be made by coprecipitation fromsolution, blending or by dry mixing together of the components, followedby melt fabrication of the dry mixture by extrusion.

Blends of the modified block copolymer of the present invention withengineering thermoplastics (ETP) which are condensation products, e.g.,polyamides, polyesters and polyurethanes, may be prepared bymelt-blending the desired proportion of ETP, ranging from about 1percent to about 99 percent, with the desired proportion of the modifiedblock copolymer, correspondingly ranging from about 99 percent to about1 percent, respectively. With these ranges, ETP/modified block copolymerblends utilizing the modified block copolymer of :he present inventioncan be a resinous composition a rubbery composition or a leather-likecomposition according to the ratio of the thermoplastic polymer as thecomponent (a) relative to the modified block copolymer as the component(b) and the alkenyl arene content of the base block copolymer of themodified block copolymer as the component (b). In the case where aresinous composition is obtained, when the alkenyl arene content of thebase block copolymer is over 60% by weight up to 99% inclusive byweight, preferably 65 to 90% by weight, the component (a)/component (b)weight ratio is adjusted in the range of from 90/10 to 5/95, preferablyfrom 85/15 to 10/90, more preferably from 80/20 to 15/85, and when thealkenyl arene content of the base block copolymer is 1 to 60% by weight,preferably 10 to 55% by weight, more preferably 15 to 50% by weight, thecomponent (a)/component (b) weight ratio is adjusted in the range offrom 50/50 up to 99/1 inclusive, preferably from 60/40 to 95/5, morepreferably from 70/30 to 90/10. When the amount of the component (b) istoo small and below the above range, no substantial effect of improvingthe impact resistance or paint adhesion is expected and when the amountof the component (b) is too large, the rigidity is expected to bedegraded. In the case where a rubbery or leather-like composition isprepared, when the alkenyl arene content of the base block copolymer is1 to 60% by weight, preferably 10 to 55% by weight, more preferably 15to 55% by weight, the component (a)/component (b) weight ratio isadjusted in the range of from 1/99 to less than 50/50, preferably from5/95 to 40/60, more preferably from 10/90 to 30/70. When the amount ofthe component (a) is too small and below the above range, no substantialimprovement of the composition as a rubbery or leather-like compositioncan be attained. When the amount of the component (a) is too large, therubbery or leather-like characteristics are lost and the compositionbecomes resinous.

The impact properties of the resinous blends utilizing the modifiedblock copolymer of this invention are believed improved as characterizedby expected higher notched Izod value over the polyamide alone or in ablend with the base (unmodified hydrogenated) copolymer, particularlywhen the alkenyl arene content of the block copolymer is from about 1 toabout 60% by weight. The amount of functionality in the modified blockcopolymer employed in such compositions will differ with the degree ofimpact properties desired. Within the broad range of 50/50 up to 99/1inclusive (component (a)/component (b) though not likely to correspondto the foregoing commercially preferably ranges, blends considered to be"super-tough" are expected to be attainable. A blend is considered to be"super-tough" herein when its 1/8" Notched Izod at room temperature isin excess of 10 ft-lb/in and the blend experiences ductile failure, asopposed to brittle failure.

The improvement in toughness of such compositions is related to theamount of adherent sites in the modified block copolymer component andthe degree of block copolymer distribution or dispersion.

The mechanism of adhesion and the role of the copolymer/ETP interface topromote rubber (block copolymer) distribution or dispersion is notentirely understood. However, it is believed that the grafting reactionand rubber dispersion are interrelated. To some extent, enhancing theextent of reaction is expected to facilitate rubber distribution ordispersion. Moreover, it is believed that by increasing the blockcopolymer/ETP interface more sites are made available for the unknownmechanism herein to operate upon. As for the morphology of the articlesmade from such blends, it is unknown whether the block copolymer may becontinuous, partially continuous or dispersed within the ETP.

Blends with Non-reactive Thermoplastic Polymers

Similarly, polymer compositions containing the modified block copolymerof the present invention may also contain thermoplastic polymers whichare not reactive with the modified block copolymer therein. Thenon-reactive thermoplastic polymers are preferably non-polar, such asstyrene polymers and olefin polymers, which are present as a separateand preferably dispersed phase therein. These thermoplastic polymers canoptionally be incorporated into the present polymer compositions toimprove the processability of the composition without substantiallydetracting from the essential character of the modified block copolymertherein. The amount of the non-reactive thermoplastic polymer ispreferably 100 parts by weight or less, more preferably 1 to 50 parts byweight based on 100 parts by weight of the continuous phase, modifiedblock copolymer.

The styrene polymers are polymer substances containing 50% by weight ormore of styrene, such as polystyrene, styrene-α-methylstyrenecopolymers, butadiene-styrene block copolymers and hydrogenatedderivatives thereof, isoprene-styrene block copolymers and hydrogenatedderivatives thereof, rubber modified high impact polystyrene, andmixtures thereof.

The olefin polymers are polymer substances containing 50% by weight ormore of an olefin monomer unit containing ethylene, propylene, buteneand the like. Typical examples of such polymers are low-densitypolyethylene, high density polyethylene, polypropylene, polybutene,ethylene-propylene copolymers and the like, including mixtures thereof.

The polymer compositions containing the modified block copolymer of thepresent invention may further contain other conventional additives.Examples of such additives are reinforcing materials such as silica,carbon black, clay, glass fibers, organic fibers, calcium carbonate andthe like, as well as stabilizers and inhibitors of oxidative, thermal,and ultraviolet light degradation, lubricants and mold release agents,colorants including dyes and pigments, nucleating agents, fireretardants, plasticizers, etc.

The stabilizers may be incorporated into these composition at any stagein the preparation of the thermoplastic composition. Preferably, thestabilizers are included early to preclude the initiation of degradationbefore the composition can be protected. Such stabilizers must becompatible with the composition.

Compositions consisting essentially of or incorporating the modifiedblock copolymer of the present invention can be molded or formed intovarious kinds of useful articles by using conventional molding,injection molding, blow molding, pressure forming, rotational moldingand the like. Examples of the articles are sheets, films, foamedproducts as well as injection-molded articles, blow-molded articles,pressure-formed articles and rotational-molded articles having variouskinds of shapes. These articles can be used in the fields of, forexample, automobile parts, electrical parts, mechanical parts, footwear,medical equipment and accessories, packaging materials, buildingmaterials and the like.

Viscosity Index Improver/Dispersant

The modified block copolymers of the present invention are expected tobe useful as additives for lubricants, in which they would functionprimarily as dispersants and viscosity modifiers. These polymers may beemployed in a variety of lubricants based on diverse oils of lubricatingviscosity, including natural and synthetic lubricating oils and mixturesthereof. Examples of such lubricating oils are disclosed in U.S. Pat.Nos. 4,145,298; 4,357,250; and 4,670,173, the disclosures of which areherein incorporated by reference. An illustrative list of suchlubricants include crankcase lubricating oils for spark-ignited andcompression-ignited internal combustion engines, including automobileand truck engines, two-cycle engines, aviation piston engines, marineand railroad diesel engines, and the like. Such lubricant compositionsmay also be used in gas engines, stationary power engines and turbinesand the like. Automatic transmission fluids, transaxle lubricants, gearlubricants, metal-working lubricants, hydraulic fluids and otherlubricating oil and grease compositions may also benefit from theincorporation therein of the modified block copolymers of thisinvention.

The modified block copolymer of the present invention preferablycontains an effective amount of nitrogen for imparting suitabledispersancy to the block copolymers which are suitable as viscosityindex improvers. Such modified block copolymers are preferablynon-network forming block copolymers to which has been grafted theeffective amount of nitrogen via a nitrogen-containing functional group,which herein is an amine group. The effective amount of nitrogen graftedthereto is at least about 0.01 percent by weight based on the base blockcopolymer more preferably from about 0.01 to ahout 5 percent by weightand yet more preferably from ahout 0.05 to about 0.5 percent by weight.Commercially available non-network forming base block copolymerssuitable for modification are available from Shell Chemical under themarks Shellvis® 40 and 50.

Generally, the lubricants of the present invention contain an effectiveamount of the modified block copolymer of the present invention fordispersing insoluble impurities and for improving viscosity properties.Normally, this amount will be from about 0.01 to about 10 percent byweight based on the total weight of the lubricant preferably from about0.5 to ahout 5 percent by weight. Formulations for different lubricantapplications are known in the art, for example, those given in U.S. Pat.No. 4,145,298, particularly in column 10, lines 16 to 32, the disclosureof which are herein incorporated by reference.

The lubricants of the present invention are also contemplated to useother additives in combination with the modified block copolymers ofthis invention. Such additives include, for example, auxiliarydetergents and dispersants of the ash-producing or ashless type,corrosion- and oxidation-inhibiting agents, pour point depressingagents, extreme pressure agents, color stabilizers and anti-foam agents.Examples of such additives are disclosed in U.S. Pat. Nos. 4,145,298;4,357,250; and 4,670,173, the disclosures of which are hereinincorporated by reference.

The modified block copolymers of this invention may be added directly tothe lubricant. Preferably, however, these block copolymers are dilutedwith a substantially inert, normally liquid organic diluent such asthose disclosed in U.S. Pat. Nos. 4,145,298; 4,357,250; and 4,594,378,the disclosures of which are herein incorporated by reference. .Theseconcentrates usually contain from about 5 to about 90 percent by weightof the modified block copolymer of the present invention based on thetotal weight of the concentrate. These concentrates may also contain, inaddition, at least one other additive known in the art or describedhereinabove.

Additionally, the modified block copolymer is expected to find utilityas a gasoline additive. Formulation guidelines and other additivesincluded therein are disclosed, for example, in U.S. Pat. No. 4,328,202(Trepka et al), the disclosure of which is herein incorporated byreference.

To assist those skilled in the art in the practice of this invention,the following Prophetic Examples are set forth as illustrations. It isto be understood that in the specification and claims herein, unlessotherwise indicated, when the amount of the ETP or block copolymer isexpressed in terms of percent by weight, it is meant percent by weightbased on the total amount of these materials. Furthermore, it is to beunderstood that, unless otherwise indicated, when the amount of aminefunctional groups is expressed in terms of percent by weight (% w), itis meant percent by weight based on the base block copolymer. Injectionmolded bars of these compositions may be tested using the following testprocedures in the dry-as-molded state:

Notched Izod toughness: at each end ASTM D-256

Flexural Modulus: ASTM D-790

EXAMPLES OF THE INVENTION

Having thus broadly described the present invention, it is believed thatthe same will become even more apparent by reference to the followingprophetic examples. It will be appreciated, however, that the examplesare presented solely for the purposes of illustration and should not beconstrued as limiting the invention.

EXAMPLE 1 Modified Block Copolymer-Amine Functionality

The formation of block copolymers having amine functionality in thestyrene segment of the copolymer would be envisioned to proceed in twosteps-(1) lithiation of the starting block copolymer followed by (2)reaction with an arylimine. Aqueous work-up of the product would afforda block copolymer having secondary amine functionality in the styrenesegment of the polymer chain.

A suitable hypothetical base block copolymer for this reaction would bean anionically polymerized styrene-butadiene-styrene (7,700-36,100-7,700block molecular weights) block copolymer having a 1,2-butadiene additioncontent greater than 35% which had been selectively hydrogenated toafford a styrene-ethylene/butylene-styrene block copolymer of the samemolecular weight bu(having less than 5% of the ethylenic (C═C)unsaturation of the starting diene polymer. This material, Polymer A,would be carried forward in the lithiation reaction using the followingprocedure.

A 5% (wt/wt) solution of Polymer A in cyclohexane (3100 lb) would betreated, in a closed vessel under nitrogen, with the metalationpromoter, N,N,N',N'-tetramethylethylenediamine (TMEDA) (14 lb, 55 mol)and a titration indicator, 1,1-diphenylethylene (21 g, 0.1 mol). Thissolution would be heated with stirring to 50° C. and titrated withs-butyllithium solution to remove impurities. At the endpoint of thetitration, a slight excess of s-butyllithium reagent would react withthe indicator forming a benzylic anion which would give the solution ayellow/orange color; the persistence of this color would be taken as anindication that the solution was now anhydrous and anaerobic. Theseconditions would be maintained throughout the rest of the experiment.

The metalation reagent, s-butyllithium (41 lb of a 12% (wt/wt) solutionin cyclohexane, 35 mo), would be added to the reaction mixture over aperiod of 15 minutes. The lithiated polymer cement would be quiteviscous and yellow in color. An aliquot of the cement would be removedand treated with an excess of D₂ O. This procedure places a deuteriumatom on the polymer at sites which had been lithiated. Analysis of thedeuterated polymer using a Deuterium NMR technique would be expected toshow that about 89% of the deuterium was attached to the aromatic ring.Appropriate control experiments would show that the remainder of thedeuterium label was at benzylic centers (about 5%) in the polystyrenesegment and at allylic centers (about 6%) in the rubber of the polymer.These results would show that the polymer was lithiated principally inthe styrene blocks (at least 94%).

The procedure for the reaction of lithiated polymer A with an arylimineis a modification of a procedure for the reaction of non-polymericlithium alkyls with benzophenone N-phenylimine as described on p. 109 in"The Chemistry of Organolithium Compounds," B. J. Wakefield, PergamonPress, Oxford, England, 1974 (see also references therein).

After 1 hour in the lithiation reactor (60° C.), the metallated polymercement would be transferred to a closed vessel containing benzophenoneN-phenylimine (9,900 g, 38.5 mol) in anhydrous tetrahydrofuran (THF)(about 380 gal). The lithiated polymer cement would be introduced belowthe surface of the imine/THF mixture. While reaction would likely beinstantaneous, the mixture would be stirred at room temperature for 4hrs. The reactor product would be neutralized by the addition of aceticacid to a phenolphthalein endpoint. The product, Polymer B, would beisolated by steam coagulation and dried at 50°-60° C. in a vacuum oven.An aliquot of isolated Polymer B would be analyzed for N (nitrogen)content using a chemiluminescence technique. Analysis would be expectedto find about 0.36% wt polymer bound N. This level of functionalitywould correspond to 13 amine sites per polymer chain. Polymer B would beexpected to be an laminated block copolymer having about 13 phenyl aminesites distributed between the two polystyrene end segments.

EXAMPLE 2 Nylon 6,6/Modified Block Copolymer Blends

ln this example, the modified block copolymer would be used as an impactmodifier in an ETP which is a condensation product, e.g. a polyamide.The thermoplastic Polyamide to be used in this example would be acommercial nylon 6,6, Zytel® 101, a molding grade nylon available fromDupont. Prior to all processing steps, the nylon 6,6 and its blend wouldbe dried at 60° C. for four (4) hours under vacuum with a nitrogenpurge. The compositions would have a fixed block copolymer to nylonratio of 30:70. The samples which would be prepared would utilize thebase-block copolymer (control, Polymer A) and modified block copolymerwith 13 amine functionality sites per molecule (Polymer B).

Blends of nylon 6,6 with both unmodified and modified block copolymerwould be prepared in a 30 mm diameter corotating twin screw extruder.The blend components would be premixed by tumbling in polyethylene bags,and then would be fed into the extruder. The extruder melt temperatureprofile would be about 240° C. in the feed zone, about 270° in thebarrel, and about 250° C. at the die. A screw speed of 350 rpm would beused. The extrudate would be pelletized. Injection molded test specimenswould be made from pelletized extrudate using an Arburg injection molder(Model number 221-55-250). Injection temperatures and pressures of about260° C. to about 300° C. and about 800 psig to about 1000 psig,respectively, would be employed during the processing operations.

The blend containing the amine functionality block copolymer (Polymer B)would be expected to possess superior impact properties over thoseblends containing the unmodified base block copolymer (Polymer A).Additionally, improvements in Impact toughness of the modified blockcopolymer/nylon blends would not be expected to sacrifice or compromisethe flexural modulus when compared to those blends containing theunmodified base block copolymer.

EXAMPLE 3 Nylon 6/Modified Block Copolymer Blends

In this example, the modified block copolymer would be combined withNylon 6 (Capron 8200 from Allied) (an ETP which is a condensationproduct) to form an impact resistant polyamide blend composition. Priorto all processing steps, the Nylon 6 and its blends would be dried at60° C. for four hours under vacuum with a nitrogen purge. Thecompositions would have a fixed block copolymer to nylon ratio of 30:70.Specimens utilizing only the polyamide and a 70:30 ratio of polyamide tounmodified block copolymer A would be prepared as controls. Polymer Bwould be utilized as the modified block copolymer at the same ratio ofpolyamide to block copolymer.

Blends of the polyamide with both unmodified and modified blockcopolymer would be prepared in a Haakee 30mm diameter corotating twinscrew extruder. The blend components would be premixed by tumbling inpolyethylene bags and then would be fed into the extruder. The extrudermelt temperature profile would be about 220° C. in the feed zone, about245° C. in the barrel and about 215° C. at the die. A screw speed ofabout 350 rpm would be used. Injection molded test specimens would bemade from pelletized extrudate using an Arburg injection molder (Modelnumber 221-55-250). Injection temperatures and pressures of about 240°C. to about 270° C. and about 600 psig to about 1000 psig, respectively,would be employed during the processing operations.

Improvements in impact resistance of the Nylon 6 blends would beexpected when the modified block copolymer is utilized over those blendscontaining the unmodified block copolymer. Moreover, the flexuralmodulus of the modified block copolymer/polyamide blend is not expectedto be compromised with the enhancement of impact toughness. The modifiedblock copolymer containing amine functionality is expected to showutility as an impact modifier for polyamide resins.

EXAMPLE 4 Polyester/Modified Block Copolymer Blends

In this example, modified block copolymer would be combined with apolyester (an ETP which is a condensation product) such as poly(butyleneterephthalate) (PBT, e.g. Valox® 310 available from GE) to form animpact resistant polyester blend composition. Prior to all processingsteps, the PBT and its blends would be dried at 60° C. for four hoursunder vacuum with a nitrogen purge. The compositions would have a fixedblock copolymer to PBT ratio of 30:70. Specimens utilizing only the PBTand a 70:30 ratio of PBT to unmodified block copolymer A would beprepared as controls. Polymer B would be utilized as the modified blockcopolymer at the same ratio of PBT to block copolymer.

Blends of the PBT with both unmodified and modified block copolymerwould be prepared in a Haakee 30 mm diameter corotating twin screwextruder. The blend components would be premixed by tumbling inpolyethylene bags and then would be fed into the extruder. The extrudermelt temperature profile would be about 230° C. in the feed zone, about240° C. in the barrel and about 240° C. at the die. A screw speed ofabout 350 rpm would be used. Injection molded test specimens would bemade from pelletized extrudate using an Arburg injection molder (Modelnumber 221-55-250). Injection temperatures and pressures of about 220°C. to about 240° C. and about 800 psig to about 1200 psig, respectively,would be employed during the processing operations.

Improvements in impact resistance of the polyester blends would beexpected when the modified block copolymer is utilized over those blendscontaining the unmodified block copolymers. Moreover, the flexuralmodulus of the modified block copolymer blend is not expected to becompromised with the enhancement of impact toughness. The modified blockcopolymer containing amine functionality is expected to show utility asan impact modifier for polyester resins.

While the present invention has been described and illustrated byreference to particular embodiments thereof, it will be appreciated bythose of ordinary skill in the art that the same lends itself tovariations not necessarily illustrated herein. For this reason, then,reference should be made solely to the appended claims for purposes ofdetermining the true scope of the present invention.

What is claimed is:
 1. A lubricant composition comprising:(a) a majoramount of a lubricating oil; and (b) a minor effective viscosityimproving amount of an oil soluble, functionalized selectivelyhydrogenated block copolymer to which has been grafted amine functionalgroups, said functionalized block copolymer comprising:(1) a base blockcopolymer which comprises(i) at least one polymer block A, said A blockbeing at least predominantly a polymerized alkenyl arene block, and (ii)at least one selectively hydrogenated polymer block B, said B blockprior to hydrogenation being at least predominantly a polymerizedconjugated diene block, and (2) wherein substantially all of said aminefunctional groups are grafted to said base block copolymer on said Ablocks, and (3) wherein said amine functional groups are represented bythe general formula ##STR12## wherein R₁ and R₂ are the same ordifferent alkyl, cycloaryl or aryl radicals and wherein R₃ is ahydrogen, alkyl, cycloalkyl, aryl or silyl radical.
 2. The compositionaccording to claim 1, wherein said minor effective amount is from about0.01 to about 10 percent by weight based on the total weight of saidcomposition.
 3. The composition according to claim 1, wherein said aminefunctional groups are present in an amount such that the nitrogencontent of said functionalized block copolymer is at least about 0.01percent by weight on said base block copolymer.
 4. The compositionaccording to claim 3, wherein the nitrogen content of saidfunctionalized block copolymer is from about 0.01 to about 5 percent byweight based on said base block copolymer.
 5. The composition accordingto claim 1, wherein said copolymer has a structure selected from thegroup consisting of A--B, B--A--B, (B--A)--_(n) X, and (B--A)--_(y)X--(B)_(z) and (B--A)--_(y) X--(A)_(z) wherein X is a residual group ofa polyfunctional coupling agent having two or more functional groups, yand z are, independently integers of 1 to 20 and n is an integer of 2 to40.
 6. The composition according to claim 1, wherein said compositionhas a branched structure.
 7. The composition according to claim 1,wherein said composition has a linear structure.
 8. The compositionaccording to claim 2, wherein(a) each of said A blocks prior tohydrogenation is at least predominantly a polymerized monoalkenylmonocyclic arene block having an average molecular weight of about 1,000to about 125,000, (b) each of said B blocks prior to hydrogenation is atleast predominantly a polymerized conjugated diene block having anaverage molecular weight of about 10,000 to about 450,000, (c) said Ablocks constituting about 2 to about 70 percent by weight of said baseblock copolymer, (d) the residual ethylenic unsaturation of said B blockis less than about 10 percent of the ethylenic unsaturation of said Bblocks prior to hydrogenation, and (e) the residual aromaticunsaturation of said A blocks is greater than about 90 percent of thearomatic unsaturation of said A block prior to hydrogenation.
 9. Thecomposition according to claim 8, wherein said A blocks constitute about20 to about 70 percent by weight of said base block copolymer.
 10. Thecomposition according to claim 8, wherein prior to hydrogenation:(a)said A block is polymerized styrene and (b) said B block is selectedfrom the group consisting of polymerized isoprene, polymerizedbutadiene, and polymerized isoprene and butadiene copolymer.
 11. Thecomposition according to claim 10, wherein said B block is polymerizedbutadiene block having a 1,2 content of between about 35 percent andabout 55 percent.
 12. The composition according to claim 11, whereinsaid polymerized butadiene block has an average molecular weight ofbetween about 10,000 to about 150,000.
 13. The composition according toclaim 12, wherein the residual ethylenic unsaturation of saidpolymerized butadiene block is less than about 5 percent of theethylenic unsaturation present prior to hydrogenation.
 14. Thecomposition according to claim 13, wherein the residual ethylenicunsaturation of said polymerized butadiene block is at most 2 percent ofthe ethylenic unsaturation present prior to hydrogenation.
 15. Thecomposition according to claim 14, wherein said polymerized styreneblock has an average molecular weight of between about 1,000 and about60,000.
 16. The composition according to claim 15, wherein prior tofunctionalization said base block copolymer is apolystyrene-poly(ethylene/butylene) diblock copolymer.
 17. Thecomposition according to claim 15, wherein prior to functionalizationsaid base block copolymer is apolystyrene-poly(ethylene/butylene)-polystyrene block copolymer.
 18. Thecomposition according to claim 10, wherein said B block is a polymerizedisoprene block.
 19. The composition according to claim 18, wherein saidpolymerized isoprene block has an average molecular weight of betweenabout 10,000 to about 150,000.
 20. The composition according to claim19, wherein the residual ethylenic unsaturation of said polymerizedisoprene block is less than about 5 percent of the ethylenicunsaturation present prior to hydrogenation.
 21. The compositionaccording to claim 20, wherein the residual ethylenic unsaturation ofsaid polymerized isoprene block is at most about 2 percent of theethylenic unsaturation present prior to hydrogenation.
 22. Thefunctionalities block copolymer according to claim 21, wherein prior tofunctionalization said base block copolymer is apolystyrene-poly(ethylene/propylene) diblock copolymer.
 23. Thecomposition according to claim 21, wherein prior to functionalizationsaid base block copolymer is apolystyrene-poly(ethylene/propylene)-polystyrene block copolymer.